2003 F-350 V10 with leveling kit and 35" tires

[ticopowell]

So my dad has a 2003 F-350 with the V10, a leveling kit and 35" tires, a K&N CAI and I believe a flowmaster muffler. He uses it as a DD in the winter because of the snow in utah, and we tow a 22' boat a few times a summer, usually not too far, but up to 300 miles a trip each way. I know that he would love to get better gas mileage and he would not mind having more power for driving and towing, so i was wondering what he can do that is relatively cheap(we both are pretty cheap) that will help this... Ive searched a bit on the forums here and on a lot of F-150 forums(thats what i own! ), and ive seen a lot of things to do, from a Gryphon(which i also own! ) to changing the gear ratio's so if anyone has any advice then please let me know so i can pass it on. Also a price estimate would be great as well! Also any advice on how to convince him to get a Gryphon would be amazing! :P
Also just another thought, i have PM'd Corey twice about my Gryphon mount in my truck, I am currently using paper wedged in there to keep it in the black plastic mount , and i am sure that there is a better way. I have seen what looks like a seal around the edge and also a back plate for the programmer, neither were included when i got my Gryphon. Any help would be great!
Sorry that this is a 2 question thread, but i figured y'all's could handle it.